Thanks for the tutorial. Bootstrap’s documentation also states that you should use autoprefixer when compiling the less/sass files.

Reference: http://getbootstrap.com/getting-started/#download-autoprefixer

“Bootstrap uses Autoprefixer to deal with CSS vendor prefixes. If you’re compiling Bootstrap from its Less/Sass source and not using our Gruntfile, you’ll need to integrate Autoprefixer into your build process yourself. If you’re using precompiled Bootstrap or using our Gruntfile, you don’t need to worry about this because Autoprefixer is already integrated into our Gruntfile.”